Write the arithmetic sequence

Question

Write the arithmetic sequence 5,10,15,20,.... the standard form:

A_n=

Answer 1

Hi Dalia

 

We notice that our sequence is increasing in multiples of 5.

 

A_n = a + (n-1)d

 

a is your first term, in this case, 5.

 

n is the nth term. For instance, 10 would be the 2nd term, 15 the 3rd term, 20 the 4th and so on....

 

d is the difference in terms, which we said to be 5.

 

Example:

 

If we wanted to find the 8th term:

 

5 + (8-1)*5 = 5 + 7*5 = 5 + 35 = 40

 

To check our answer we have:

 

5, 10, 15, 20, 25, 30, 35, 40

 

We see that 40 is the 8th term is our sequence, therefore our arithmetic is correct.